WNK (With No Lysine [K]) kinases comprise a unique branch of the human kinome that appear to be responsible for a wide variety of cellular functions. Mutations of these genes cause human hypertension and have identified them as part of a novel signaling mechanism in the kidney. WNK1, WNK3, and WNK4 have distinct properties to stimulate or inhibit salt transport, effects that can be modified based on physiological need. The WNK signaling complex hypothesis postulates that the kidney specific effects of WNK kinases are mediated by the unique convergence of four members of the WNK kinase family within distal nephron cells. The proposed experiments will elucidate the nature of this complex by demonstrating where the WNK kinases are expressed along the nephron, how WNK3 and WNK4 interact to regulate salt transport, and how a kidney-specific kinase-deficient WNK signals to WNK3 in kidney. It has been demonstrated recently that WNK kinases also mediate aldosterone signaling to the thiazide-sensitive salt transporter. The proposed work will address the mechanisms involved. This work will involve heterologous expression in Xenopus oocytes and epithelial cells. The second aim will move the work toward more physiologically relevant model systems by examining the effects of increased abundance of the thiazide-sensitive transporter and by developing models to delete or increase expression of WNK kinases specifically along the distal nephron. Specifically, they will test the results of cell-specific knockout or knockin of WNK3. The results will substantially enhance both the understanding of the WNK signaling complex and provide avenues for developing drugs that enhance salt excretion without affecting potassium balance. Project Relevance: Hypertension is the most common disease in the United States. There is a large genetic component, but the nature of the genetic basis is unclear. WNK kinases regulate blood pressure in animals and humans. This work holds the possibility not only of improved understanding of blood pressure regulation but also of developing new, safer and more effective drugs to treat this important disease. PUBLIC HEALTH RELEVANCE: Hypertension is the most common disorder of Americans, accounts for billions of dollars of cost, and costs millions of lives. A large portion of hypertension is related to genetics. This proposal will help unravel genetic contributions to human blood pressure variation, with the goal of finding better treatments, or better preventive maneuvers.